Which Victron Controller Do I need?

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scubacollie asked May 10, '22

Which Victron Controller Do I need?

Hi, I'm installing 2 x 175W RENOGY Mono Solar Panels wired in Series

I've ordered 10Awg cable, and run will be approx 18ft.

Batteries are 2 x 150Ah AGM wired in parellel.

Ive used the Victron calculator but I've had to guess a few figures as it's not on the Spec sheet for the panels.

It's telling me I need a 100/50 Controller? Does this sound right as I had to guess a few figures?

Also, I have an original panel that is linked to the existing split charge system via a rocker switch which I can change to charge either the starter battery or the leisure batteries. I'm going to leave this as it is and can then charge the leisure batteries with this as well as the two new panels effectively having 3 x solar panels in total charging the leisure batteries if required. However this panel has an existing PWM controller and I would like to also change this to a Victron at the same time, but I don't have any info on that panel as it came with the van. I think it's a 120W Pro Logic panel.

Therefore to summarise I need to purchase 2 x Victron Smart Controllers, one for the two new Renogy Solar panels. And one to replace the existing PWM controlled for use with the existing Pro Logic panel.

Can somebody please assist as I don't find it very easy to chose Victron controllers and I'm sure Victron would sell a lot more if they made it easier for customers.

victron products

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Answer 1 · 2022-05-10T03:06:38Z

kevgermany answered · May 10, 2022 at 03:06 AM

Matching panels and controllers is a complex business and expensive if wrong. The calculator is to help. To recommend properly you'll have to give us the data sheet for the panels.

However, the model numbers indicate max input voltage and max output current. Battery voltage is auto sensed. Take the panel's max voltage, Voc and double it. That's your first number. Controller voltage must be higher. Check coldest temperature. Make sure the difference between panel and mppt is big enough to accommodate voltage increase in mid winter using a base of 25C.. Panels are 175W So 350W max. Could be higher in very sunny areas. Work on a charge voltage of 14. 350/14=25, So a 30A controller is good.

For the existing panel, it's guesswork. I'd pick a 10A charger with the lowest voltage over a guess of a panel max voltage of 30. There should be a sticker on the back of the panel giving it's specs, if you can get at it. One caveat. The max panel voltage must be at least 5V higher than actual battery voltage before charging starts. Assume battery voltage is charge voltage from the dual panels, say 14.6V. So the panel must deliver close to 20V to get charging going.

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scubacollie commented · May 12, 2022 at 10:46 PM

Hi mate can I just please query regarding the controller for the 2 x 350 Renogy (Datasheet in above link) I've been trying to get the Victron calculator to match the 75/10 model recommended above but it keeps telling me either 100/30 or 100/50 depending on if I put in 1 x 350 watt panel or 2 x 150 watt panels..... But neither state 75/10?

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Answer 2 · 2022-05-10T06:32:14Z

scubacollie answered · May 10, 2022 at 06:32 AM

Hi Kevgermany, really appreciate your assistance.

Please see below information from the listing where I purchased it from (the Renogy Store on Amazon).

Max Power at STC: 175W
Open Circuit Voltage: 21.6V
Short Circuit Current: 10.35A
Opitmum Operating Voltage: 17.95V
Optimum Operating Current: 9.75A
Operating Temperature: -40°F to 176°F

I have also found the below Datasheet on the Renogy Website which I 'believe' is for the same panel?

I've uploaded it here to my Google Drive account https://drive.google.com/file/d/1J9hyWWt9PFgaV78OENUyScSJ-dD8HLi1/view?usp=drivesdk

Also it states on the above Datasheet that the panels Optimum Operating Voltage is only 17.95V does this mean its no good to get charging going for my 2 x 150Ah AGM batteries wired in parallel giving me 300Ah?

I believe I need around 14.7V charge on these AGM's....

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Answer 3 · 2022-05-10T10:16:01Z

kevgermany answered · May 10, 2022 at 10:16 AM

To start, battery +5V, to keep charging battery 1V. So panels perfect.

Probably just a sanity check needed on winter voltages, the data sheet shows -0.3%V/C. So at 0C you have an increase of about 2V. If you go for the 75/10, plenty of headroom.A second 75/10 for the old panel.

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scubacollie commented · May 12, 2022 at 10:47 PM

Hi mate can I just please query regarding the controller for the 2 x 350 Renogy (Datasheet in above link) I've been trying to get the Victron calculator to match the 75/10 model recommended above but it keeps telling me either 100/30 or 100/50 depending on if I put in 1 x 350 watt panel or 2 x 150 watt panels..... But neither state 75/10?

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kevgermany ♦♦ scubacollie commented · May 13, 2022 at 05:10 AM

Sorry. I'm mixing your systems.

There's no 75/30, which is why it's recommending the 100/30.

The 350W panel can produce over that on very sunny days, which would push you up to the 100/50

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